Earth's 'sixth great extinction event'

P opulation growth, pollution and invasive species are having a disastrous effect on species in the southern hemisphere, a major review by conservationists warns.

Earth is experiencing its "sixth great extinction event" with disease and human activity taking a devastating toll on vulnerable species, according to a major review by conservationists.Much of the southern hemisphere is suffering particularly badly, and Australia, New Zealand and neighbouring Pacific islands may become the extinction hot spots of the world, the report warns.

Ecosystems in Polynesia, Micronesia and Melanesia need urgent and effective conservation policies, or the region's already poor record on extinctions will worsen significantly.Researchers trawled 24,000 published reports to compile information on the native flora and fauna of Australasia and the Pacific islands, which have six of the most biodiverse regions on the planet.

Their report identifies six causes driving species to extinction, almost all linked in some way to human activity.

"Our region has the notorious distinction of having possibly the worst extinction record on Earth," said Richard Kingsford, an environmental scientist at the University of New South Wales in Sydney and lead author of the report. "We have an amazing natural environment, but so much of it is being destroyed before our eyes. Species are being threatened by habitat loss and degradation, invasive species, climate change, over-exploitation, pollution and wildlife disease." The review, published in the journal Conservation Biology, highlights destruction and degradation of ecosystems as the main threat.In Australia, agriculture has altered or destroyed half of all woodland and forests. Around 70 per cent of the remaining forest has been damaged by logging. Loss of habitats is behind 80 per cent of threatened species, the report claims.Invasive animals and plants have devastated native species on many Pacific islands.

The Guam Micronesian kingfisher is thought to be extinct in the wild following the introduction of the brown tree snake.

The impact of humans on wildlife is likely to increase in Australasia and the Pacific islands. By 2050, the population of Australia is expected to have risen by 35 per cent, and New Zealand by per cent, while Papua New Guinea faces a 76 per cent increase and New Caledonia per cent.More than 2,500 invasive plant species have colonised Australia and New Zealand, competing for sunlight and nutrients. Many have been introduced by governments, horticulturists and hunters. In addition, the report says, average temperatures in Australia have increased, in line with climate change predictions, forcing some species towards Antarctica and others to higher, cooler ground.The report highlights several studies that point to serious threats from diseases such as avian malaria and the chytrid fungus, linked to declines in frog populations.

An infectious facial cancer is spreading rapidly among Tasmanian devils and populations of the world's largest marsupial predator are believed to have fallen greatly as a result.Plants have also fared badly: a root fungus deliberately introduced into Australia has destroyed several species.

The report sets out a draft of recommendations to slow the decline by introducing laws to limit land clearing, logging and mining; restricting deliberate introduction of invasive species; reducing carbon emissions and pollution; and limiting fisheries.

It raises particular concerns about bottom trawling, and the use of cyanide and dynamite, and calls for early-warning systems to pick up diseases in the wild.

-Guardian

Giant statues reveal red hat secrets

British archaeologists said on Monday, September 7 they believe they have solved the ancient mystery of how the giant stone statues on Easter Island acquired distinctive red hats.

The researchers said the key to the mystery lies in their discovery of a road on the tiny Pacific island.

The hats were built in a quarry hidden inside the crater of an ancient volcano, and then rolled by hand or on tree logs to the site of the statues, said the team from the University of Manchester and University College, London.The archaeologists examined the way the hats, each weighing several tons and made of red scoria, a pumice-like volcanic rock, were moved by Polynesians between 500 and 750 years ago.

They were placed on the heads of carved stone human figures known as moai standing on ceremonial platforms which encircle the island's coastline.But the riddle of how they were raised and attached remains unsolved.Dr. Colin Richards from the University of Manchester said: "We now know that the hats were rolled along the road made from a cement of compressed red scoria dust with a raised pavement along one side.

"It is likely that they were moved by hand, but tree logs could also have been used." Dr. Sue Hamilton, of University College, London, said: "The hat quarry is inside the crater of an ancient volcano and on its outer lip. A third of the crater has been quarried away by hat production."So far we have located more than 70 hats at the ceremonial platforms and in transit. Many more may have been broken up and incorporated into the platforms." Richards said there was evidence the quarry, known locally as Puna Pau, had previously produced statues before changing to hats.

"Initially the Polynesians built the moai out of various types of local stone, including the Puna Pau scoria, but between 12,000 to 13,000 AD, Puna Pau switched from producing statues to hats. The change correlated with an increase in the overall size of the statues across the island."

AFP

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